Godot: Fit RichTextLabel to text

RichTextLabelWithFitToText.gd

extends RichTextLabel

var width_adjust = 1.4

var default_font = get("custom_fonts/normal_font")

# Array of string representing multi-line text.
func set_text(lines:Array):
  clear()
  for ln in lines:
    add_text(ln)
    newline()
  fit_to_lines(lines)

func fit_to_lines(lines:Array):
  var size = max_extents(lines)
  size.x *= width_adjust
  set_size(size)

func max_extents(lines:Array):
  var sizes = line_sizes(lines)
  var widths = []
  var sum_height = 0
  for s in sizes:
    widths.append(s.x)
    sum_height += s.y
  return Vector2(widths.max(), sum_height)

func line_size(line:String):
  return default_font.get_string_size(line)

func line_sizes(lines:Array):
  var sizes = []
  for ln in lines:
    sizes.append(line_size(ln))
  return size